1. Field of the Invention
The present invention relates to an image forming apparatus that is connectable to a network, and an operation system and an operation method which realize power saving of the image forming apparatus.
2. Description of the Related Art
An image forming apparatus, for example, a digital multi-function machine called MFP (multi-function peripherals), has a scanner unit and a printer unit. A document is read by the scanner unit. The read image data is processed by an image processing unit. The image is printed by the printer unit.
Some of the recent digital multi-function peripherals have a facsimile function using a public line, as well as a copy and scanner functions. Some of the digital multi-function peripherals also have plural functions such as connecting to a network and getting linked to an external computer (for example, a personal computer), inputting print data from the external computer, and printing the data.
Such digital multi-function peripherals have taken various measures to reduce power consumption. For example, JP-A-2005-288971 discloses an image forming apparatus in which the time for shifting to a sleep state or a ready state can be preferentially set by user operation. However, in this example, the time of power-saving operation is set by the user and only simple settings can be provided.
JP-A-2005-32397 discloses a power saving control method. In this example, the state of power in plural image forming apparatuses connected to a network is centrally controlled by using a power saving server. However, in this example, it is determined whether the total value of power consumption by the image forming apparatuses exceeds a target value or not, and the overall power consumption of the system is reduced. This technique has a problem that the overall control algorithm is inflexible and has a low degree of freedom.